In treating a gas stream or flue gas, dry flue gas desulfurization (DFGD) systems are known. Typically, in DFGD processes, lime (CaO) is first converted to hydrated lime (Ca(OH)2) before use by contact with the flue gas to be treated. The hydrated lime is placed in contact with the flue gas as a dry or moistened powder within a circulating dry scrubber (CDS) DFGD system. An example of such a CDS DFGD system is the ALSTOM NID™ system (ALSTOM Power Inc., Paris, France) (NID).
WO 97/37747, invented by Stefan Ahman et al., discloses a device for a CDS DFGD system useful for discharging and distributing an absorbent material in a flue gas duct. Accordingly, in a vertical flue gas duct for flow of flue gases containing gaseous pollutants, the absorbent material discharging and distributing device is arranged. The arranged device discharges and distributes a particulate absorbent material reactive with the gaseous pollutants in the flowing flue gas to convert the gaseous pollutants to a separable dust.
While methods and equipment capable of removing both particulate and gaseous pollutants from a flue gas stream exist, there remains a need for improved DFGD systems with reduced footprint fabric filter systems to reduce associated costs, to allow for installation in existing plants having limited available space, and to allow for future system expansion, while maintaining system stability, efficiency and effectiveness.